calcium sulfate

A salt (CaSO . H 2 O), very slightly
soluble in water. In its natural form, it may
exist as anhydrite (CaSO 4 ) or gypsum
(CaSO 4 . H 2 O) It is used
as a filler pigment in the manufacture of paper.
Precipitated calcium sulfate is known as "crown
filler," or "pearl filler." See also: BRIME .